Long-term safety and tolerability of entecavir in patients with chronic hepatitis B in the rollover study ETV-901

Objective: To review long-term safety data from the rollover study ETV-901, focusing on adverse events (AEs) with a potential nucleos(t)ide association. Methods: The open-label study ETV-901 (AI463901) assessed the safety of entecavir in chronic hepatitis B patients who received entecavir, lamivudine or adefovir monotherapy in previous entecavir Phase II/III studies. Long-term cumulative safety results are based on reported AEs, regardless of causal relationship. Results: Median exposure to entecavir in study ETV-901 was 184 weeks. Commonly reported AEs (≥ 10%) were upper respiratory tract infection, headache and nasopharyngitis. Most AEs were mild to moderate; 203 (19%) patients reported grade 3 4 AEs, with 45 (4%) considered related to entecavir. There were 14 (1%) discontinuations due to AEs. On-treatment alanine aminotransferase (ALT) flares were reported in 32 (3%) patients and were associated with a reduction in hepatitis B virus DNA of more than 2 log10 copies/ml in 25/32 patients. AEs potentially associated with nucleos(t)ide analogs were infrequent, the most common being myalgia (n = 54; 5%) and neuropathy-related AEs (hypoparesthesia and hyperparesthesia, polyneuropathy; n = 42; 4%). Conclusions: Long-term administration of entecavir was associated with low rates of serious AEs, discontinuations due to AEs and ALT flares. AEs potentially associated with nucleos(t)ide use occurred at low rates.